Woods' upturn continues at Pebble Beach

(CNN) -- Former world No. 1 Tiger Woods' recent upsurge in form continued on the first day of the AT&T Pebble Beach National Pro-Am as the 14-time major winner carded a four-under-par 68 in his opening round of the PGA Tour season.

The U.S. event is played over three courses, with Woods playing Thursday's round on the Spyglass course -- traditionally the most difficult of the courses used at the California golf club.

Despite a challenging start, Woods finished just five strokes off the lead, which was shared by world No. 10 Dustin Johnson, South Korean Charlie Wi and New Zealand's Danny Lee.

Woods' round included six birdies and just two bogeys and was only two strokes off compatriots Nick Watney and Kevin Na's mark of 66 -- Thursday's lowest round at Spyglass

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"Friday will be an important day to put it together and make some birdies," the 36-year-old told the Tour's official website.

"You have to have to the right mindset ... I feel comfortable because of my practice sessions. I'm able to actually practice, which I hadn't been able to for a very long time."

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Woods has history at this event and at this venue, having won the tournament in 2000 before going on to win the U.S. Open at the club in June the same year.

The American, who has not won an officially sanctioned tournament since November 2009 but finished third in Abu Dhabi last month, was optimistic ahead of tackling the Monterey Peninsula course in round two.

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"With the scores the way they are, I thought I could have it lower than I did. The guys are just tearing this place apart with no wind. I'm not too far away from posting a good number out here," he said.

The U.S. duo of Ken Duke and Brian Harman, who both played the Pebble Beach Links course, were tied on eight under after carding opening rounds of 64.

Watney and Na were two strokes further back and tied for sixth with Josh Teater, who carded a 64 at Monterey Peninsula.

Also on six under was Canada's Graham DeLaet following a 66 on Pebble Beach Links.

Woods was in a 12-way tie for 15th which also included Fiji's former world No. 1 Vijay Singh -- who shot 68 on Pebble Beach Links.

Jim Furyk, the 2003 U.S. Open winner, was one of 14 players on three under, while four-time major champion Phil Mickelson (70) and Ireland's Padraig Harrington (68), a winner of three majors, were both on two under.